134 articles
Lakh (लाख)
Lakh (लाख), also spelled lac, is a unit in the Indian numbering system equal to one hundred thousand, the standard large-number word in South Asian finance and everyday speech.
Large numbers
Large numbers, or very large numbers, are numbers far beyond everyday counting, conventionally starting around a million, expressed through -illion names, scientific notation, SI prefixes, and googology.
Long and short scales
The long and short scales are two competing systems for naming large numbers: in the short scale each new term is 1,000 times the previous one, in the long scale 1,000,000 times.
Look-and-say sequence
The look-and-say sequence, also called the Conway sequence or audioactive decay, is an integer sequence where each term describes the previous one, giving 1, 11, 21, 1211, 111221.
Lucas number
The Lucas numbers, also known as the Lucas series, are an integer sequence 2, 1, 3, 4, 7, 11, where each term is the sum of the two before it.
Lucas numbers
Lucas numbers form an integer sequence 2, 1, 3, 4, 7, 11, defined by the Fibonacci recurrence but with different starting values, named for Édouard Lucas.
Lucas sequence
A Lucas sequence is one of a pair of integer sequences defined by a recurrence with parameters P and Q, generalizing Fibonacci, Pell, and Mersenne numbers.
Lucky number
A lucky number is a positive integer surviving a position-based sieve invented at Los Alamos in 1956 as a variation of the sieve of Eratosthenes.
Macdonald polynomials
Macdonald polynomials are a two-parameter family of symmetric polynomials indexed by partitions, introduced by Ian G. Macdonald in 1987 to unify the Hall-Littlewood and Jack symmetric functions.
Myriad
A myriad is, precisely, the number ten thousand, the largest number named by one word in ancient Greek; in modern English it loosely means an indefinitely great number.
Names for the number 0 in English
English has several names for the number 0: zero, the general term; oh for reading digits; nought in British use; nil for sports scores; and love in tennis.
Names of large numbers
Names of large numbers are the English words for powers of ten beyond a thousand, coined from Latin with the -illion ending, as in million, billion, and trillion.
Narayana number
The Narayana numbers, named for the Canadian mathematician T. V. Narayana, form a symmetric triangular array counting Dyck paths with k peaks; row sums give the Catalan numbers.
Narcissistic number
A narcissistic number, also called an Armstrong number, is a number equal to the sum of its digits each raised to the number of digits, like 153.
Number of the beast
The number of the beast, also called the beast number (Greek: Χξς), is 666, given in Revelation 13:18 as the number of a beastly figure who forces everyone to receive a mark.
On-Line Encyclopedia of Integer Sequences
The On-Line Encyclopedia of Integer Sequences (OEIS), also called Sloane's OEIS, is a free online database of integer sequences, online since 1996 and holding over 400,000 entries.
Padovan sequence
The Padovan sequence, also called the Cordonnier sequence, is an integer sequence defined by P(n) = P(n−2) + P(n−3), named by Ian Stewart in 1996.
Palindromic number
A palindromic number, also called a numeral palindrome, reads the same forwards and backwards in some base, such as 121 or 94200249 in decimal.
Partition function (number theory)
The partition function p(n) counts the ways a nonnegative integer can be written as a sum of positive integers, ignoring order; for example, p(4) = 5.
Partition numbers
The partition numbers p(n) count the ways a nonnegative integer n can be written as a sum of positive integers, ignoring order; the sequence begins 1, 1, 2, 3, 5, 7.
Perfect numbers
A perfect number is a positive integer equal to the sum of its proper divisors, such as 6 and 28; every even one arises from a Mersenne prime.
Perfect power
A perfect power is a positive integer that can be written as m^k, with m > 1 and k at least 2, such as 4, 8, 9, and 27.
Plane partition
A plane partition is a partition of an integer n whose parts are arranged in a two-dimensional array, weakly decreasing across rows and down columns.
Power of 10
A power of 10 is a number like 100 or 1000, written 10 to the nth power, that underlies decimal notation and the SI metric prefixes.
Power of two
A power of two is a number written as 2 to a whole-number exponent, beginning 1, 2, 4, 8, 16, 32, and important in computing.
Practical number
A practical number is a positive integer such that every integer up to n is a sum of distinct divisors of n; 12 is the classic example.
Primorial
The primorial is the analog of the factorial for primes: the product of the first n primes, or all primes up to n, written n#.
Pronic number
A pronic number, also known as an oblong or heteromecic number, is a number that is the product of two consecutive integers; the sequence begins 0, 2, 6, 12, 20.
Ramanujan's congruences
Ramanujan's congruences are three divisibility properties of the partition function p(n), discovered by Srinivasa Ramanujan in 1919: p(5n+4), p(7n+5), and p(11n+6) are divisible by 5, 7, and 11.
Ramanujan's lost notebook
Ramanujan's lost notebook is a manuscript of over 600 formulas written without proofs by the Indian mathematician Srinivasa Ramanujan, found by George Andrews in Cambridge in 1976.